Bentonite clay is commonly used to retain water within diaphram walls during construction. A disadvantage of this material is that the clay must be disposed of after it has served its purpose.
Ullmans Encyclopadie der technischen Chemie, 4th Edition, Vol. 9, pp. 192,209, refers to the use of water-soluble cellulose ethers such as sodium carboxymethylcellulose for use for diaphram wall construction. Modified cellulose ethers and their use as thickeners and dispersion agents are described in U.S. Pat. Nos. 4,228,277, 4,336,146, 4,720,303 and 4,799,962.
But in spite of what was previously published and known to workers in the construction field, prior attempts to use cellulosic polymers for diaphram wall construction were not completely satisfactory due to the inability to prevent water loss from the filled trench into the surrounding soil. As a result, clay continued to be used for diaphram wall construction in spite of the environmental advantages of the use of a biodegradable polymer such as cellulose.